Surface treatment applicance, a filter and components therefor

ABSTRACT

A cyclone filtration assembly unit is described. The unit is configured to mount in a vacuum cleaner, and includes a housing having a housing inlet for a dirty air stream and a housing outlet for a filtered air stream; one or more cyclone separators mounted in the housing, each of the one or more cyclone separators comprising one or more cyclone separator inlets, at least one dirt outlet, and at least one clean air outlet in fluid communication with the housing outlet; and one or more injector units configured to deliver an airstream of clean air from outside the housing and dirty air from inside the housing to the one or more cyclone separator inlets, the injector unit comprising: a diffuser duct having an inlet end in fluid communication with the housing inlet to introduce dirty air from the housing inlet to the cyclone separator inlet, and an injector tube configured to inject clean air into the diffuser duct adjacent the inlet end, the injector tube being in fluid communication with a housing aperture at an inlet end to introduce clean air from outside the housing to the diffuser duct.

FIELD

The present technology relates generally to surface treatment appliances, including vacuum cleaners, floor washers and the like. The present technology also relates to filters for use in surface treatment appliances, and to filter components.

BACKGROUND

Surface treatment appliances which utilise cyclone separation devices are known.

Cyclone separation devices, for high performance, are dependent on good air velocity in the cyclone. Each dirt, be it dust or another kind of particulate matter, which spins with an air stream within the cyclone has working upon it a certain centripetal force, and that centripetal force is related to velocity, mass and radius in accordance with the known formula: F=mv²/r.

Since force depends on the square of the velocity, the velocity is the most important factor in cyclone separation. In vacuum cleaners with cyclones, when the air stream velocity is reduced, the performance of the cyclones is reduced. For example, when a crevice tool or other nozzle of a vacuum cleaner is partially blocked, the velocity of the air in the vacuum cleaners cyclone separation device decreases and that cyclone separation device won't function properly. If the crevice tool or other nozzle is fully blocked then the cyclone separation device will completely stop its filtration/dust separation function.

So the performance of the cyclone separation device is dependent on the crevice tool or other nozzle's engagement with the surface to be treated, and that engagement level is constantly changing, ranging from fully blocked to fully open. Some vacuum cleaners utilise a relief aperture in the hose between the crevice tool or other nozzle, and a dust chamber, to maintain at least some air flow into the hose and cyclone separation devices even when the crevice tool or other nozzle is completely blocked at the surface to be treated. Such holes cause significantly reduced suction at the surface to be treated. Some vacuum cleaners lose more than 50% suction because of the relief aperture. Also, if a large object such as a tissue blocks the entrance well downstream of the relief aperture, say, at the dust chamber, then the relief aperture is of no assistance.

Some known vacuum cleaners are provided with a bypass valve downstream from the cyclone filters, and immediately upstream of the motor, in case there is a blockage somewhere in the machine, either at the floor nozzles, or somewhere downstream from there. The bypass valves are important, and particularly ones immediately upstream, because they would very quickly burn out if there was no airflow to them. These are emergency valves and their operation results in immediate loss of suction at the floor nozzles, and loss of cyclonic filtration in the body of the machine. Clearly this is undesirable and the machines sometimes require a total reset to continue their operation.

In machines with a bypass valve, the valve is set to stay closed until the vacuum pressure inside the hose or cyclones reaches about −30 kPa, and the airstream becomes choked and slow well before that level of suction is reached. Indeed, it has been observed that at −20 kPa the air stream has already commenced slowing and reducing. However, if the bypass valve is set to trip at −20 kPa then the machine will not provide good suction.

Some machines utilise bypass valves upstream of the cyclonic filters but they have been found to very quickly become clogged with dirt.

The present technology seeks to ameliorate one or more of the abovementioned disadvantages, and/or at least provide a new filter, and/or a useful filter alternative, and a new or useful surface treatment appliance.

SUMMARY

Broadly, the present technology in operation injects a stream of clean air into a dirty air stream and diffuses the injected clean air with the dirty air inlet stream to form a diffused air inlet stream upstream of a cyclone separator inlet.

Advantageously, it can be seen from reading this disclosure as a whole that embodiments of the technology disclosed herein create greater suction at the nozzle head engaged with the floor as well as draw in more air to the cyclones to maintain filter performance to separate the dirt drawn in by the greater suction. Other known related machines focus only on drawing more air into the cyclone separators to provide better centripetal dust separation performance.

Broadly, in another aspect the present technology provides an injector for introducing clean air to a dirty air stream and providing a diffused air stream upstream of a cyclone separator inlet.

Broadly in one aspect the present technology provides a cyclone separator with an injector immediately upstream of a cyclone inlet for introducing clean air to a dirty air stream to provide a diffused clean and dirty air stream immediately upstream of the cyclone separator. The diffused clean and dirty air stream is accelerated by the injector to improve filtration performance.

Broadly in one aspect the present technology introduces atmospheric pressure or forced pressure clean air to a dirty air stream to create higher suction at the floor nozzle and a higher-velocity air stream at the floor nozzle and a cyclone separator for improved separation. In some embodiments it is an advantage to provide a short path for the clean air to an injector and/or cyclone separator to reduce resistance to the clean air and reduction of pressure loss before the air reaches an injector tube and cyclone separator.

Broadly in one aspect the present technology provides a surface treatment apparatus with at least one cyclone separation filter including an injector and a diffuser for introducing clean air to a dirty air stream and providing a diffused air stream immediately before the air stream is introduced to the cyclone separation filter.

Broadly, in another aspect there is provided an injector which converts energy of forced-pressure air or atmosphere pressure air in a hose, to suction at a nozzle and high velocity air stream in a cyclone.

Broadly in another aspect there is provided by the present technology a De Laval nozzle or De Laval injector or Venturi injector which extends along a tortuous path. The tortuous path in some embodiments ends at a diffuser outlet which is in fluid communication with a cyclone separator.

Broadly, the present technology provides an integrated vacuum cleaner and compressor.

In accordance with a first aspect of the present invention there is provided a cyclone filtration assembly unit for mounting in a vacuum cleaner, the cyclone filtration assembly unit including:

a housing having a housing inlet for a dirty air stream and a housing outlet for a filtered air stream;

one or more cyclone separators mounted in the housing, each of the one or more cyclone separators comprising one or more cyclone separator inlets, at least one dirt outlet, and at least one clean air outlet in fluid communication with the housing outlet; and

one or more injector units configured to deliver an airstream of clean air from outside the housing and dirty air from inside the housing to the one or more cyclone separator inlets, the injector unit comprising:

-   -   a diffuser duct having an inlet end in fluid communication with         the housing inlet to introduce dirty air from the housing inlet         to the cyclone separator inlet, and     -   an injector tube configured to inject clean air into the         diffuser duct adjacent the inlet end, the injector tube being in         fluid communication with a housing aperture at an inlet end to         introduce clean air from outside the housing to the diffuser         duct.

In one embodiment the diffuser duct is a venturi arrangement, wherein adjacent the injector tube there is a throat portion being a restriction in the diameter of the diffuser duct.

In one embodiment the diffuser duct includes an outlet in fluid communication with an associated cyclone separator, the diffuser duct being configured to mix the clean airstream with the dirty air stream.

In one embodiment the diffuser duct is disposed on a tortuous path.

In one embodiment filtration assembly unit in accordance with any one of claims 1 to 4 wherein the tortuous path is a helix.

In one embodiment a valve is provided in fluid communication with the injector tube to control clean air inlet flow therethrough.

In one embodiment there is provided an electronic controller for the valve, the electronic controller being configured to respond to changes in pressure in the diffuser duct.

In one embodiment there is provided a valve closure element operatively connected to a pressure-responsive element that is responsive to changes in pressure in the diffuser duct.

In one embodiment the venturi throat portion or venturi restriction and the valve are integrally-formed so as to provide a variable choke in the diffuser duct and fresh air injection with a response to reductions in pressure in the diffuser duct.

In one embodiment there is provided a biasing element to bias the valve closure element, the biasing element disposed in a clean air duct.

In one embodiment the injector tube is angled relative to the diffuser duct so as to provide accelerated the dirty air in the diffuser duct.

In one embodiment the throat section of the diffuser duct is variable in internal diameter in response to changes in pressure in the diffuser duct.

In one embodiment the throat section of the diffuser duct includes flexible walls so as to vary the internal cross section area of the diffuser duct.

In one embodiment a regulator is integral with the wall of the diffuser duct and arranged to respond to a low pressure in the diffuser duct by choking the throat.

In one embodiment the regulator responds to low pressure in the diffuser duct by opening an aperture in the injector tube to allow fresh air into the diffuser duct.

In one embodiment the injector tube is in fluid communication at the housing aperture to a vacuum cleaner motor to provide forced clean air induction through the injector.

In one embodiment the injector unit is a De Laval nozzle arrangement such that the nozzle is a converging nozzle for delivering clean air to the diffuser, and there is then downstream from there, a diverging region for mixing and converting the kinetic energy of the flow to pressure.

In one embodiment the diverging region is adjacent the dirty air inlet, and the diffuser duct then converges again to provide more kinetic energy and further mixing, and then downstream from the diffuser duct, at its outlet, delivery of the mixed fluid to the cyclone separator element.

In one embodiment the injector inlet is angled at between 110 and 150 degrees to the diffuser duct to reduce pressure loss therein.

In one embodiment the injector tube has a cross-sectional area of between about 15% and 35% of the cross sectional area of the diffuser duct to provide greater suction and efficiencies of filtering.

A vacuum cleaner including:

a hose and nozzle inlet for drawing dirt from a surface;

a motor for drawing air through the hose and nozzle inlet;

a cyclone filtration assembly unit as hereindescribed.

In one embodiment the injector is associated with a primary cyclone separator.

In one embodiment the injector is associated with a secondary cyclone separator, downstream of the primary cyclone separator.

According to one aspect of the present invention there is provided a method of filtering dirt from a dirty air stream, the method including the steps of:

-   -   introducing a stream of clean air into the dirty air stream         through an injector;     -   mixing the stream of clean air with the dirty air stream in a         diffuser disposed immediately upstream of a cyclone separator to         form a mixed air stream; and     -   introducing the mixed air stream to the cyclone separator for         cyclonic separation.

According to one aspect of the present technology there is provided an injector for use in a surface treatment appliance, the injector including:

-   -   a clean air inlet for introducing clean air into a diffuser;     -   a dirty air inlet for introducing dirty air into the diffuser;         and     -   a diffuser duct for mixing the clean and dirty air immediately         upstream of the cyclone separator.

According to one aspect of the present technology there is provided a cyclone separator for filtering dirt from a dirty air stream, the cyclone separator including:

-   -   a mixed air inlet for introducing a mixed air stream to the         cyclone separator for filtration;     -   a diffuser duct for mixing clean air with dirty air, the         diffuser duct comprising:         -   an injector for injecting clean air into the diffuser duct;         -   a dirty air inlet port for introducing dirty air into the             diffuser duct;         -   a mixed air diffuser outlet;     -   wherein the mixed air diffuser outlet is in fluid communication         with the mixed air inlet of the cyclone separator.

According to one aspect of the present technology there is provided a secondary cyclone filtration assembly unit for mounting in a vacuum cleaner filter canister downstream of a primary filter for secondary filtering, the cyclone filtration assembly unit including;

-   -   one or more cyclone separators, each one having a cyclone         separator inlet, a dirt outlet and a clean air outlet;     -   an injector configured to deliver a mixed airstream of         primary-filtered air from a clean side of the primary filter and         clean air from outside the vacuum cleaner to each cyclone         separator inlet.

In one embodiment the injector includes one or more dirty air inlets configured to draw a dirty air stream through the primary filter.

In one embodiment the injector includes a diffuser having an outlet in fluid communication with the inlet of the one or more cyclone separators, the diffuser being configured to diffuse the clean air with the dirty air stream.

In one embodiment the injector includes an inlet duct having an inlet duct end and an inlet duct outlet end, the outlet end being in fluid communication with a manifold.

In one embodiment the manifold includes a plurality of ducts connecting the outlet end of the inlet duct to a plurality of injector tubes.

In one embodiment each one of the injector tubes includes a converging nozzle end with a nozzle outlet being adjacent a dirty air inlet, the converging nozzle end and dirty air inlet being at an upstream end of the diffuser.

In one embodiment the diffuser is a duct which provides mixing of the clean and dirty air to provide a mixed air stream for delivery to the inlet of the one or more cyclone separators.

In one embodiment the or each injector extends generally along an outside wall of a respective cyclone separator, generally parallel with a cyclone longitudinal axis, radially spaced to an inside thereof. When there are a plurality of injectors, or an injector assembly, it may be most suitably disposed radially to an inside of a radial arrangement of cyclone separators to facilitate efficient use of space.

In one embodiment the injector inlet duct is disposed at a centre of the secondary cyclone filtration assembly, and each one of the diffuser ducts is spaced radially outwardly therefrom, but not as radially far from the inlet duct as the cyclone separators themselves, to facilitate the retention of as much kinetic energy as possible when the air is introduced into the diffuser and the cyclone separators.

In one embodiment there may be provided a forced induction to the inlet. A separate motor or, in one embodiment, the same motor providing the suction from the surface to be treated, may be used to force clean air into the injector via a forced air injector duct.

In one embodiment the injector arrangement is a De Laval nozzle arrangement such that the nozzle is a converging nozzle for delivering clean air to the diffuser, and there is then downstream from there, a diverging region for mixing and converting the kinetic energy of the flow to pressure. The diverging region is adjacent the dirty air inlet. The diffuser duct then converges again to provide more kinetic energy and further mixing, and then downstream from the diffuser duct, at its outlet, delivery of the mixed fluid to the cyclone separator element.

It will be understood that this is the Venturi effect and for greater clarity the operation is described in more detail below and in conjunction with FIG. 29. That is, the Venturi effect can be explained by Bernoulli's equation:

$p_{2} = {p_{1} - {\frac{p}{2}\left( {v_{2}^{2} - v_{1}^{2}} \right)}}$

wherein:

-   -   p₂ is dirt air inlet pressure,     -   p₁ is atmosphere pressure (ambient air pressure)     -   p₄ is suction pressure from suction fan.     -   p₃ is compressed air pressure.     -   v₂ is speed of fresh air. (created by atmosphere pressure p₁ or         by compressed air p₃ and v₂ is proportional with p₁ and p₃), and     -   v₁ is speed of dirty air stream.

Also, it is to be understood that p is the density of the fluid (kg/m³). For air that quantity is 1.2 kg/m³ approximately when the temperature is 0° C.

According to one aspect of the present technology there is provided a surface treatment appliance including:

-   -   a hose and nozzle inlet for drawing surface dirt from a surface;     -   a motor for drawing air through the hose and nozzle inlet;     -   a filter unit including:     -   a cyclone separator for filtering dirt from a dirty air stream,         the cyclone separator including:     -   a mixed air inlet for introducing a mixed air stream to the         cyclone separator for filtration;     -   a diffuser duct for mixing clean air with dirty air, the         diffuser duct comprising: an injector for injecting clean air         into the diffuser duct; a dirty air inlet port for introducing         dirty air into the diffuser duct; and     -   a mixed air diffuser outlet;     -   wherein the mixed air diffuser outlet is in fluid communication         with the mixed air inlet of the cyclone separator.

In one embodiment the injector is associated with a primary cyclone separator. In one embodiment the injector is associated with a secondary cyclone separator, downstream of the primary cyclone separator. In one embodiment the injector is associated with a tertiary cyclone separator.

In one embodiment the cyclone separator is a primary cyclone separator although the cyclone separator may be a secondary cyclone separator downstream from the primary cyclone separator or a tertiary cyclone separator downstream from the secondary cyclone separator.

In one embodiment there is provided a primary or secondary or tertiary cyclone separator assembly which includes a plurality of cyclone separator filter elements, each one having a diffuser inlet, a dirt outlet, a cyclone separator body and a clean air outlet.

In one embodiment the primary or secondary or tertiary cyclone separator assembly includes a plurality of cyclone separator elements, a dust chamber disposed at the dirt outlets of the cyclone separator elements, and an injector assembly.

In one embodiment the injector assembly includes one or more clean air inlet ducts, one or more clean air manifolds, one or more clean air injector ports, one or more dirty air inlets and one or more diffuser ducts.

In one embodiment there is provided a primary or secondary or tertiary cyclone separator assembly which includes six cyclone separator elements. There may be secondary cyclone separator assemblies which include one, two, three, four, five, six, seven, eight, nine, ten, eleven, twelve, thirteen, fourteen, fifteen, sixteen or any other suitable number of cyclone separator elements.

In one embodiment the cyclone elements may be radially arranged such that they are spaced around a central point, such that their longitudinal axes are generally parallel with one another and parallel with a central axis. It is to be understood that the longitudinal axes may be slightly turned in and may have other tiered features as is described herein and shown in the drawings. The arrangement may be on a square of say 200 mm side, or other like spaced arrangement.

In accordance with another aspect of the present invention there is provided a method of filtering dirt from a dirty air stream flowing in a duct, the method including the steps of:

-   -   introducing a stream of clean air through an injector duct into         the duct;     -   mixing the stream of clean air with the dirty air stream in a         diffuser disposed immediately upstream of a cyclone separator to         form a mixed air stream; and     -   introducing the mixed air stream to the cyclone separator for         cyclonic separation.

In accordance with still another aspect of the present invention there is provided an injector for use in a surface treatment appliance, the injector including:

-   -   a clean air inlet duct for introducing clean air into a         diffuser; a dirty air inlet duct for introducing dirty air into         the diffuser duct; and     -   a diffuser duct for mixing the clean and dirty air immediately         upstream of the cyclone separator.

In accordance with another aspect of the present invention there is provided a crevice tool for use with a vacuum cleaner, the crevice tool including:

-   -   a nozzle body having an inlet configured to suck dirt from         crevices and an outlet for affixing to a vacuum cleaner hose;     -   an injector tube connected to the nozzle body and extending         therefrom to inject clean air from a position remote from the         inlet.

In embodiments the nozzle body inlet is angled from the nozzle body to facilitate reaching into crevices.

In embodiments the injector tube is angled to the nozzle body to facilitate acceleration of clean air into the nozzle body.

In embodiments the injector tube is about 10% to 33% of the diameter of the nozzle body at the outlet.

In embodiments the injector tube is disposed adjacent the outlet.

In embodiments the injector tube length is about 2 to 10 times the diameter.

In embodiments a valve is provided in the injector as hereindescribed for other embodiments. In embodiments the valve is structured and controlled as hereindescribed for other embodiments.

A cyclone filtration assembly unit for mounting in a vacuum cleaner, the cyclone filtration assembly unit including:

-   -   a housing having a housing inlet for a dirty air stream and a         housing outlet for a filtered air stream;     -   one or more cyclone separators mounted in the housing, each one         of the one or more cyclone separators comprising one or more         cyclone separator inlet ducts, a dirt outlet, and a clean air         outlet in fluid communication with the housing outlet;     -   an injector unit configured to deliver a clean airstream of         clean air from outside the housing to the one or more cyclone         separator inlet ducts, the injector being in fluid communication         with a housing aperture to introduce clean air from outside the         vacuum cleaner to the one or more cyclone separator inlet ducts.

Injector Theory—Venturi Principle

But as discussed with reference to FIG. 21 the structure of this technology is not exactly the same as a conventional Venturi pump, because the driving force is from suction source p₄ and not from the suction nozzle engaged with the floor. The suction fan inside the pump delivers a negative pressure; the normally aspirated air from the injector becomes a higher pressure-driven fluid. So the dirty air inlet pressure p₂ is affected by both driven fluid pressure p₁ and suction pressure p₄, such that (p₁) is positive or driven pressure and the other (p₄) is negative or suction pressure. If the air from the injector is compressed air p₃, forced by a fluid communication (tube) with the rear of the vacuum cleaner motor, then the suction at the nozzle head engaged with the floor will be much greater. The conventional Venturi pump only has one driven force p₃, however it is to be understood that in embodiments of this disclosure the structure is termed an “injector”.

The Bernoulli formula cannot fully explain the injector but is a close enough approximation to explain the working principle as there is no such formula for the injector in a vacuum cleaners readily available, and it is extremely difficult to make a mathematical model give a complete description of the injector.

In operation, the handheld nozzle of the vacuum cleaner will engage with a floor surface, and the speed of dirty air v₁ will be slower than the fresh air v₂. That is:

-   -   v₂>v₁

So p₂ is always negative compared with atmosphere pressure p₁ (when vacuum cleaner is operating), because high speed v₂ will create a suction force at dirty air inlet under the Venturi effect. Then, v₂ is created either by atmosphere pressure p₁ or compressed air pressure p₃ If the speed of v₂ is more greater than v₁, then p₂ is more negative, and the overall effect is to create more suction at dirty air nozzle inlet.

Interestingly, p₂ can be less than p₄ thus:

-   -   p₄>p₂

Known vacuum cleaners do not operate in this manner. Other known vacuum cleaners operate such that dirty air inlet suction p₂ only depends on suction fan's air pressure p₄, and thus p₂ is either same as p₄ or greater. Therefore, in the known vacuum cleaners, dirty air inlet never has more suction than the suction fan. But in this disclosure, preferred embodiments provide an injector which makes the dirty air inlet provide more suction pressure than the suction fan. This is why when we have great suction (−30 kpa) at handheld nozzle we do not trip the bleed valve when it is present in an embodiment of the disclosure. In some models of vacuum cleaner, the bleed valve is tripped at −25 kpa. The valve is close to suction fan and there is less suction compared with handheld nozzle.

Especially when compressed air used, v₂ can be far higher than v₁ and p₂ can be very low. Thus it can be seen that the embodiments of the disclosure, when implemented, create more suction at the dirty air inlet of the injector and along the wand to the handhold nozzle of vacuum cleaner.

It can be seen that even while more air passes into the cyclone dust separator, the cyclone increases its efficiency. If the vacuum cleaner is not drawing dirty air off the floor surface, (say, if the handheld nozzle end is in the middle of the air) then

-   -   p₂=p₁, and v₂=v₁, (if no compressed air used) and     -   the injector doesn't have any effect. But in this situation,         embodiments of the technology of the present disclosure don't         need the injector to have any effect.

However, if compressed air p₃ is used, then

-   -   v₂>>v₁ and therefore the injector creates more suction at dirty         air inlet and whether the handheld nozzle is engaged with the         floor surface or not is irrelevant.

And herein lies at least one of the advantages of embodiments described in the present disclosure: broadly speaking, the embodiments described in the present disclosure create greater suction at the nozzle head engaged with the floor. Other known related machines only focus on drawing more air into the cyclone separators to provide better centripetal dust separation performance. It can be seen that embodiments described in this disclosure draw in more air and create greater suction at the same time.

The injector tube does not necessarily converge but may be a straight pipe which expands abruptly into a diffuser. In one embodiment the dirty air inlet is angled at 135 degrees to reduce pressure loss in the diffuser duct. The angle may be any suitable angle such as for example 110, 120, 130, 140, 150 or 180 or the like for reducing losses. In experiments it has been assessed that when the angle 9 is 135°, the duct has good air flow rate but there may be a lower suction present at that arrangement than for a 90° angle bend in the diffuser. The figure of angle 9 may be further refined by particular suction and air flow rate requirements of particular vacuum cleaner contexts and applications. A lower angle provides more suction but a lower flow rate. It may be that an angle of 135° may be a preferred angle for a vacuum cleaner.

In one embodiment the diverging portion of the diffuser may be a ball or it may be an ellipse for greater mixing and reduction of losses.

In one embodiment the nozzle may not just be converging, but it may be much smaller in cross sectional area than the downstream portions of the diffuser, in particular the dirty air inlet, which is adjacent but just downstream from the injector tube. It may be advantageous for the injector tube to have a cross-sectional area of between 0.5% and 35% of the cross sectional area of the throat or mixer (between the dirty air inlet and the diffuser) dirty air inlet to provide greater suction and efficiencies of filtering. In some embodiments the cross sectional area of the injector tube will be about 20% of the cross sectional area of the throat.

Although, as described herein, the diffuser duct may run parallel to the cyclone separator and the injector inlet duct, in one embodiment the diffuser is a helical arrangement disposed at a top end of the cyclone separator. The helical arrangement is a walled duct, and the inner wall may provide an outer wall for a clean air outlet for the cyclone separator. That is, the clean air outlet duct for the cyclone separator passes through the inside of the helical diffuser.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to enable a clearer understanding of the present technology, example embodiments will hereinafter be described with reference to the attached drawings, which all show embodiments of the present technology and in which:

FIG. 1 is an isometric view of a cyclone filter with multiple injector units, showing that each injector unit has a dirty inlet port and a clean injector tube, the latter in use connected to an aperture in a vacuum cleaner filter housing so as to access air at atmospheric pressure and cleanliness;

FIG. 2 is an isometric view of the cyclone filter shown in FIG. 1 with a secondary set of cyclone filters downstream of the cyclone in FIG. 1, the second stage also having an injector unit with a manifold to distribute the mixed air to the secondary stage cyclones, shown more clearly in FIG. 3;

FIG. 3 is an isometric view of the second stage, shown with injector assembly;

FIG. 4 is an isometric view of a two-stage cyclonic filter arrangement, both stages with injectors of embodiments of the present technology;

FIG. 5 is an isometric view of another multiple-cyclone filter stage, with a manifold connected to injector units;

FIG. 6 is an isometric view of a valve assembly for use in the injector units to limit fresh air flow except in the event of a blockage, which would reduce the pressure inside the diffuser duct;

FIG. 7 shows an isometric view of an electronically-controlled valve, including pressure sensor;

FIG. 8 shows an isometric cutaway view of a regulator (valve) integrated with the injector tube so that a pressure reduction in the diffuser duct causes the regulator to choke the diffuser duct and also draw in fresh air, in one movement;

FIG. 9 shows the regulator (valve) in an open position, which would be the choke position in response to a reduction in pressure.

FIG. 10 shows a view of a valve arrangement responsive to a reduction in pressure in the diffuser duct, and shows a variable throat element disposed in the wall of the diffuser duct;

FIG. 11 shows a view of the arrangement of FIG. 10 but in a block event, where there is some blockage in the system and there is low pressure in the diffuser duct;

FIG. 12 shows another valve arrangement to control clean air entry into the diffuser duct via the injector tube;

FIG. 13 is a section view of the variable throat element shown in FIG. 10;

FIG. 14 is a cyclone filtration assembly unit cut away for clarity, with the clean air injector valve closed, vacuum cleaner in normal operation;

FIG. 15 is the cyclone filtration assembly unit shown in a blockage situation, and the fresh air injector valve is actuated and the venturi throat is deployed into the choke position to facilitate acceleration of the clean air and dirty air mix therethrough;

FIG. 16 is similar to FIG. 16 but with boots to inhibit dirt in the moving parts;

FIG. 17 is a cutaway view of a cyclone filtration unit having helical diffuser ducts at entry to the cyclone separators and a central fresh air inlet duct and manifold;

FIG. 18 is a cutaway view of the cyclone arrangement of FIG. 17 showing the manifold spokes;

FIG. 19 is another embodiment of cyclone arrangement with central manifold clean air injectors;

FIG. 20 is a similar view of the cyclone arrangement of FIG. 19;

FIG. 21 is a cutaway view of an injector unit showing diffuser duct and injector tube for discussing theory;

FIG. 22 is an isometric view of a crevice tool with injector tube;

FIG. 23 is a vacuum cleaner floor head;

FIG. 24 is a vacuum cleaner floor head with handle portion;

FIG. 25 is a schematic view of a forced-induction injector unit with air extracted from the vacuum cleaner motor;

FIG. 26 is a schematic view of another forced-induction injector unit;

FIG. 27 is a helically-wound diffuser duct with injector tube;

FIG. 28 is a cyclone filtration assembly unit housing; and

FIG. 29 is an injector arrangement.

DEFINITIONS

Throughout this specification and the claims that follow, the word “clean” as related to air streams, is intended not necessarily to convey a complete absence of dirt, but to denote a stream of air taken from ambient or atmospheric air at atmospheric pressure, which is taken from a region that is a selected distance from a dirty floor surface to be treated. The term “clean” is distinct from dirty air from on the dirty floor surface, which is to say an air stream which has entrained in it, a plurality of dirt associated with that dirty surface.

In the same way, the term “dirt” is to be understood as being not limited to earth clumps, but is to be understood as including fine dirt, dust, chaff, and other particles large and small, as well as hair and other inert floor-dwelling elements.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIGS. 1 to 3 and 28 show a cyclone filtration assembly unit 14 which can be provided with increased air flow and suction when provided with tangentially-disposed injector units 25 mounted around the rim circumference of the cyclone 14.

The cyclone filtration assembly unit 14 is configured to be mounted in a vacuum cleaner (not shown), and the cyclone filtration assembly unit 14 includes a housing (99 in FIG. 28 but not shown in FIG. 1 for clarity) having a housing inlet 98 for a dirty air stream and a housing outlet 97 for a filtered air stream. There is one cyclone separator 14 mounted in the housing 99, the cyclone 14 having a plurality of cyclone separator inlets 16, one dirt outlet 18, one clean air outlet 20 in fluid communication with the housing outlet 97. There are a plurality of injector units 25 configured to deliver an airstream of clean air from outside the housing 99 and dirty air from inside the housing to the one or more cyclone separator inlets 16. Each injector unit comprises a diffuser duct 35 having an inlet end in fluid communication with the housing inlet 98 to introduce dirty air from the housing inlet to the cyclone separator inlet, and an injector tube 42 configured to inject clean air into the diffuser duct adjacent the inlet end, the injector tube being in fluid communication with a housing aperture 96 at an inlet end to introduce clean air from outside the housing 99 to the diffuser duct 35.

Structure and operation is as described herein, with injector tube or injector tubes 42 in fluid communication with outside air apertures 96 by a tube or manifold, either by natural aspiration or forced induction as shown in FIGS. 25 and 26. The injector units also introduce dirty air 27 through the diffuser duct inlet end, which is in fluid communication with the dirty air from the floor.

FIG. 2 and FIG. 3 show a second filtration stage downstream from the cyclone in FIG. 1, in which the filtered air from the cyclone 14 is drawn into a manifold for further cyclonic filtration via galleries tangentially disposed at the entrance of the second cyclone stages. Part of the twice-filtered air can be drawn back and injected into nozzles 42 as discussed hereinbefore or the nozzles 42 in the second stage can be connected to the outside high pressure air by apertures 96.

FIG. 3 shows that the first and second stages may include injecting nozzles as herein described for increasing the efficiency of the filtration.

FIG. 4 shows that the injector nozzle either in de Laval form shown in FIG. 29, or venturi or straight, may be used in various places to increase the efficiency of the cyclonic separation by introducing naturally aspirated clean air or forced clean air, including as shown, in a duct between two stages of a multi-stage cyclonic separator shown in cutaway for clarity.

Some arrangements of cyclonic filtration units may lend themselves to satellite or orbiting second-stage filtration arrangements as shown and described hereinabove, or to more rectilinear arrangements as shown in FIG. 5, where two manifolds 39 are arranged parallel to one another and feed a bank of parallel cyclones for second-stage filtration. Again, each entry to each cyclone includes a nozzle fed by twice-filtered air and/or clean air, depending on whether the air is forced or naturally-derived, from manifold 39, to mix with the dirty air from port 27.

The cyclone filtration assembly units 10 shown in FIGS. 17, 18 19 and 20, are configured to be mounted behind a primary filter 15 for secondary filtering. The cyclone filtration assembly unit 10 shown in FIG. 17 includes six cyclone separators 14, each one having a cyclone separator inlet 16, a dirt outlet 18 and a filtered or clean air outlet 20. The cyclone separators 14 are radially arranged such that a longitudinal axis 15 of each one extends generally parallel to a central axis 17. The cyclone separators 14 are disposed generally on a pitch circle of approximately 200 mm diameter, but of course that diameter may change depending on the capacity and other characteristics of the vacuum cleaner—for example there may be long, thin arrangements, square arrangements, or wider arrangements as discussed herein.

The dirt outlet 18 of the cyclone separators 14 is in fluid communication with a dirt chamber 30 for retention of dirt from the dirty air stream. In the cyclone filtration assembly unit 10 shown in FIG. 1, the dirt chamber 30 is disposed at a base end of the cyclone filtration assembly unit 10 to at least partially utilise gravity in keeping the dirt in the dirt chamber 30, at least when the vacuum cleaner 5 is not operating, and for ease of release of the dirt from the dirt chamber 30.

A housing is not shown for clarity but it includes a housing inlet for connecting to a vacuum cleaner hose which transports dirt from a dirty surface. There is a housing outlet through which the filtered air stream travels after being through any one of the cyclone separators 14.

The cyclone separators 14 may be frusto-conical as shown in FIGS. 19 and 20, but may also be horn-shaped as shown in FIGS. 17 and 18. The horn-shaped cyclone injectors provide some performance improvements over frusto-conical shaped separators in some conditions. The horn-shaped separators include a straight or regular cylindrical inside wall for at least a portion of the inside wall and then include a belly in an entry portion of the cyclone and taper into a head end at the dirt outlet 16. This provides a broad separation area at the belly where the clean air inlet is, so that there is less likelihood of drawing dirt out of the clean air outlet, and rapidly draws the dirt out to the centre of the dirt outlet, thus providing a vertical space advantage. In some embodiments the cyclone separators 14 are cylindrical with a dome head which appears as a bullet shape.

The cyclone filtration assembly unit 10 further includes an injector unit 25 configured to deliver a mixed airstream 26 of dirty air 27 from a clean side of the primary filter and clean air 28 from outside the vacuum cleaner to each cyclone separator inlet 16. The injector unit 25 comprises three main parts:

one or more clean air inlet ducts 36, (plus injector tube 41);

one or more dirty air inlets 32 and

one or more diffuser ducts 35.

The injector unit 25 includes six diffuser ducts 35 having dirty air inlets 32 configured to draw a dirty air stream, each one into an associated cyclonic separating filter 14. In the embodiment shown in the Figures, each one of the six dirty air inlets 32 draws air through a primary filter for secondary filtering in the cyclone separators 14, the primary filter being a passive or active mesh or other screen filter 40, with or without a dirt absorbing medium.

As mentioned, the injector unit 25 further includes six diffuser ducts 35 having an outlet in fluid communication with the inlet 16 of the one or more cyclone separators 14, the diffuser ducts 35 being configured to diffuse (or mix) the clean air 28 with the dirty air stream 27 to provide the mixed air stream 26.

As mentioned, the injector unit 25 also includes a clean air inlet duct 36 having an inlet duct end 37 and an inlet duct outlet end 38, the outlet end being in fluid communication with a manifold 39. The manifold 39 includes a plurality of clean air distributor ducts 41 connecting the outlet end 38 of the clean air inlet duct 36 to the diffuser 35.

In addition, each one of the clean air distributor ducts 41 includes an injector tube 42. That is, each one of the injector tubes 42 includes an opening into the diffuser 35. The injector tube 42 may be a converging nozzle outlet as shown in FIG. 29 or a straight tube. The injector tube 42 may in some arrangements be a converging portion of a continuous injector tube as shown in the De Laval nozzles shown in FIG. 29. Generally speaking, the injector tube 42 outlet generally opens on to or is in fluid communication with and adjacent a dirty air inlet 32, the injector tube 42 end and dirty air inlet 32 being disposed at an upstream end of the diffuser 35.

As mentioned above, the diffuser duct 35 is a duct which provides mixing of the clean air 28 and dirty air 27 to provide the mixed air stream 26 for delivery to the inlet end 16 of the one or more cyclone separators 14. The duct can be any suitable shape to facilitate fitment into the space envelope, and the diffuser duct 35 in that regard can be helical as shown in FIG. 27 or the diffuser duct can be straight. To be clear, the injector tube 42 can be connected to the outside apertures 96 in the housing 99 by tubes and a manifold if necessary.

Although mainly for space considerations, but also for efficient performance, most or all of the injector is generally disposed radially inside the cyclone separator 14, the clean air inlet duct 36 being disposed, in most of the embodiments herein contemplated, along the central axis of the cyclone filtration assembly unit 10 and adjacent an outside wall of a respective cyclone separator, generally parallel with a cyclone longitudinal axis, radially spaced to an inside thereof.

When there are a plurality of diffuser ducts 35, or an injector assembly, they may be most suitably disposed radially to an inside of a radial arrangement of cyclone separators to facilitate efficient use of space and efficient performance.

In one embodiment the injector inlet tube 42 is disposed at a centre of the secondary cyclone filtration assembly, and each one of the diffuser ducts is spaced radially outwardly therefrom, but not as radially far from the inlet duct as the cyclone separators themselves, to facilitate the retention of as much kinetic energy as possible when the air is introduced into the diffuser and the cyclone separators.

In one embodiment as is shown in FIG. 29, the injector arrangement is a De Laval nozzle arrangement such that the nozzle is a converging nozzle for delivering the clean air to the diffuser, and there is then downstream from there, a diverging region for mixing and converting the kinetic energy of the flow to pressure. The diverging region is adjacent the dirty air inlet. The diffuser duct then converges again to provide more kinetic energy and further mixing, and then downstream from the diffuser duct, at its outlet, delivery of the mixed fluid to the cyclone separator element.

As mentioned, the injector tube may not converge in some arrangements but may be a straight pipe which is in fluid communication with and expands into a mixer portion 43 of the diffuser duct 35. In some embodiments the diffuser duct 35 is straight. The expansion into the mixer portion 43 can be abrupt or can be gradual and there may be a mixing bowl (FIG. 29) as part of the mixer portion which is a ball or it may be an ellipse for greater mixing and reduction of losses.

In one embodiment the dirty air inlet is angled at 135 degrees to reduce pressure loss in the diffuser duct 35. The angle may be any suitable angle such as for example 110, 120, 130, 140, 150, or 180 or the like for reducing losses. In experiments it has been assessed that when the angle 9 is 135°, the duct has good air flow rate but there may be a lower suction present at that arrangement than for a 90° angle bend in the diffuser. The figure of angle 9 is to be further determined by suction and air flow rate requirements. A lower angle provides more suction but a lower flow rate. It may be that an angle of 135° may be a preferred angle for a vacuum cleaner.

The injector tube 42 may not just be converging, but it may be much smaller in cross sectional area than the downstream portions of the diffuser 35, in particular the dirty air inlet 27, which is adjacent but just downstream from the injector tube 42. The injector tube has a cross-sectional area of between 0.5% and 35% of the cross sectional area of the dirty air inlet to provide greater efficiencies of filtering. It has been identified in tests of selected embodiments that the injector in certain embodiments should have a cross sectional area of about 20% of the CSA of the dirty air inlet for optimum performance when using atmospheric air, but a smaller cross sectional area ratio for forced air induction such as when using the vacuum motor for forcing air back into the clean air inlet.

It is to be understood that the forced air induction can be multistage.

Thus, as shown in FIG. 25 as well as FIG. 26 and discussed here together with reference to other Figures there is provided in some embodiments a forced induction to the injector clean air inlet 36. In that embodiment, a separate motor or, in the embodiment shown, the same motor which provides the suction from the surface to be treated, is used to force clean air into the injector tube 41, 42 via the clean air inlet 37 via a forced air injector duct extending from the outlet end of a vacuum motor 9.

This forced induction may be delivered in such a way that at least a portion of filtered air which has been processed through two-stage cyclone filtration may be taken and forced back into a filtration circuit (shown in FIGS. 25 and 26) via a de Laval nozzle 1 (which corresponds with nozzle 42). The forced filtered air mixes in the mixer 3 and diffuser 4 (diffuser 35) provides additional velocity to the dirty air in the one or more dust separator cones 5 (corresponding in other Figures with one or more cyclones 14).

FIG. 26 shows the forced induction being implemented by a take-off duct 9 from a compressor 10, which draws clean air faster through a de Laval injector (1, 2, 3) by injecting super velocity dual-stage filtered air into an injector tube 1 to draw clean air through the inlet 2 so as to be mixed and then forced into a second injector tube 4 to draw dirty air faster into the cyclone 14 (7 in FIG. 26). This has the effect of substantially increasing the cyclone efficiency by imparting a higher velocity to the dirt in the dirty air stream for separation in the cyclone 14, due to the centripetal force on the dirt.

So much for the basic model. In the basic model, the air from the injector tubes 42 is constantly flowing. In these embodiments it is useful to have a permanent restriction in the diffuser to improve the flow. Other embodiments are described where the clean air is controlled by a valve which maintains good flow in the diffuser duct and does not require a choke except when the clean air is flowing.

With regard to FIGS. 22, 23 and 24, a nozzle is provided at an upper portion of a hand-held vacuuming wand shown in FIGS. 23 and 24. The arrangement is such that at least in preferred embodiments, where

S₁—Nozzle CSA (cross sectional area)

S₂—Throat CSA

S₃—Clean air outlet CSA (Total CSA of cyclone cone centre ports) or the total of the cyclone outlet ports 20 in the Figures, the nozzle in the wand will work well by maintaining

-   -   S₁=about 10-33% S₂.

That is, when the injectors of FIGS. 22 to 24 are naturally aspirated, the CSA of example injectors work well when they are sized between 10% and 33% of mixer (throat). Also, the hand wand injector works well when

-   -   S₂=about 30-55% S₃.

This is because, due to the variable centripetal forces on the dirt and dust the cyclone, the CSA of the clean air outlet 20 is only about 30-55% effective. Now, the diffusers of the wand injector are disposed well upstream of the cyclone, and therefore the CSA of the wand diffuser should not be reduced anywhere along the circuit to the filtered outlet of vacuum cleaner. So the mixer (throat) size S₂ should be the narrowest point between injector and filtered outlet.

Furthermore, the axis of injector tube, in example embodiments shown in at least FIGS. 22 to 24 and others, should be generally in alignment with the axis of the mixer and diffuser.

A nozzle closure is provided at the upper end of the wand so as to close the nozzle when the wand is in use; because of the additional air holes at the nozzle inlet adjacent the foot, the efficiency of the cyclonic filtration suffers unless the nozzle at the hand wand end is closed.

Although, as described herein, the diffuser duct may run parallel to the cyclone separator and the injector inlet duct, in one embodiment the diffuser is a helical arrangement disposed at a top end of the cyclone separator. The helical arrangement is a walled duct, and the inner wall may provide an outer wall for a clean air outlet for the cyclone separator. That is, the clean air outlet duct for the cyclone separator passes through the inside of the helical diffuser.

In operation the motor draws air through the dirty air inlets and clean air inlets. The dirty air passes up through the floor head, through the flexible duct, then into the body of the machine through the primary filter 40, which filters out some dust into a primary dust chamber. Then, that once-filtered air passes into the dirty air inlets 27 for secondary filtering. At the same time, clean air 28 from outside the vacuum cleaner filter chamber is also drawn into the injector 25, down through inlet duct 36, through the manifold 39, distributor tubes 41 and through to a nozzle 42 and then mixed in a diffuser 35 either straight or helical. In the straight diffuser a single inlet tube extends down through the centre of the assembly 10 and then into manifold 39 and then back up along a straight diffuser 35 and into a cyclone inlet 16 for separation in the cyclone body 14.

The roughly 5% to 50% clean air addition assists filtering by keeping air flow velocity high in the cyclone separators 14, slightly dilutes it to reduce wear on the inside walls, and particularly assists filtering in situations where the crevice tool/floor nozzle is blocked and dirty air flow velocity is compromised.

In the embodiments described and contemplated, the injected clean air should be imbued with relative pressure compared with the dirty air. The injected air can be high pressure air from the output of a centrifugal fan or compressor of the vacuum cleaner, as shown in FIG. 25 or 26. That is, the atmosphere can be the energy source for the injected clean air, since the vacuum cleaner is a low pressure system. These advantages are provided by the injector.

Valve Control of Injector

One embodiment which, during testing and modelling, has shown improved results over the basic model, includes a valve 50 operatively connected to the injector 25 so that the clean air is only injected when it is required because of some blockage somewhere in the circuit. The valve 50 is configured to control flow in the injector 25, in particular, in the injector tube 42. This disclosure herein contemplates and discloses, with reference to FIGS. 6 to 16, a plurality of different kinds of valve 50 and a plurality of different kinds of valve control.

In one embodiment shown, in FIG. 6, there is provided one form of automatically-actuating valve 50 operatively connected to the injector. The valve 50 is disposed in the injector tube 42 and includes an actuating assembly 52 which includes a pitot tube 54 or pressure transfer tube 54 having an open end 55 at the diffuser end. The pitot tube 54 is in fluid communication with the diffuser 35 at the diffuser end and is in fluid communication with a pressure-responsive valve actuator 56 at a valve end. In the embodiment shown, the pressure-responsive valve actuator 56 is a membrane 57 closing off the pitot tube, and is thin enough and of a suitable material to respond to air pressure changes in the small-diameter pitot tube. Thus, the material may be rubber, silicon or like material.

The membrane 57 is connected to a movable valve closure element 58 which is configured to move between a closed and an open position (closed shown in FIG. 6). The valve closure element can be a cone shape, or can be some other suitable shape, in order to provide selected valve control characteristics. The cone shape shown in the pictures provides linear control characteristics.

In operation, if the crevice tool/floor nozzle becomes wholly blocked, a vacuum or low pressure zone forms in the hose and the pitot tube 54 is exposed to the vacuum pressure in the diffuser duct 35. The membrane 57 is drawn toward the pitot tube 54 and the membrane 57 then moves the valve closure element 58 off its seat to an open position to allow fresh/clean air in to the diffuser 35 through the clean air inlet 42 either connected to the outside of the vacuum cleaner or a selected clean spot inside the vacuum cleaner. It can be seen that the fresh air connected to the injector tube 42 flows in through the valve to keep as much suction as possible at the floor nozzle level, but also to keep air flowing through the cyclones to maintain filtration capacity for any dust which may be drawn through the hose. It is also critical to keep as much air as possible flowing through the system when the motors are running because the motors will quickly burn out if no air is delivered to them.

If there is only a partial blockage in the nozzle 12, the air pressure at the floor nozzle is still much less than atmosphere in the diffuser 35 and a vacuum forms in the hose and diffuser 35. Then, the valve closure element 58 is drawn to the open position and air flows through the injector tube 42. Because the injector 25 operates on the Venturi principle (if there is a constriction in the diffuser 35), the diffuser 35 will be subject to more negative pressure, and the valve closure element 58 will be drawn open further. The result will be that the injector valve will keep air flowing in the cyclones and the motor, as well as maintain suction due to the vacuum in the hose.

In the embodiments shown in FIGS. 6 and 7, the valve closure element is conical. The air flow rate in the clean air nozzle 42 depends on the magnitude of the opening of the valve closure element and that is influenced by the size of the negative pressure at the nozzle and that depends on the size of the blockage at the floor nozzle. These air flow quantities and movements of the valve are programmed in to the controller, discussed below in relation to FIG. 7. That is, when there is a partial blockage at the floor nozzle there will be required a small air flow from nozzle tube 42, and when there is a total blockage at the nozzle there will be required full opening of the nozzle injector. With linear control there is an improved performance than known bleed valves in known vacuum cleaners.

There is also shown in FIG. 8 an integral automatic constriction which is caused to create a venturi constriction at the same time as the fresh air is inlet to the diffuser duct 35 through inlet tube 42.

Advantages

The valve can be opened to a fully open position to get good air flow to the cyclones, to maintain good performance of cyclone dust separator and motor cooling. Known bleed valves are not predictable in their performance and do not deliver good air flow in their associated ductwork because as soon as the bleed valve opens, the air pressure behind the bleed valve will increase and then the bleed valve is limited from further opening.

When the bleed valve opens in known vacuum cleaners, the suction of the vacuum cleaner is significantly reduced. Some known vacuum cleaners have to turn off the power and turn on again to reset the bleed valve to get the normal suction back. The valve described in preferred embodiments herein limits the reduction of suction when in operation. Known bleed valves normally open at or near −30 kpA, which is almost the maximum negative pressure which can be delivered by the vacuum cleaner. However, well before that pressure is reached, the performance of the cyclone separator has already been diminished and is not receiving enough air flow and the motor has already been damaged by being too hot. If the bleed valve actuation set point is reduced, then the vacuum cleaner will not deliver strong suction. The valve of the present technology, which opens in a linear, more controlled way, can be opened at −14 kPa even less, because there is little if any reduction of suction at the floor nozzle when it opens.

Airwatt Calculations

The valves of the present technology has improved airwatt figures as set out below.

-   -   Airwatt relationship:

P=0.117354*F*S

-   -   where     -   P is the power in airwatts,     -   F is the rate of air flow in cubic feet/minute.     -   S is the suction capacity as a pressure in head of water.

So, when air flow rate F is high, and suction S is high, the airwatt figure increases.

It is to be understood that various embodiments like those abovedescribed, and falling within the spirit, scope and ambit of the abovedescribed embodiments are intended to be covered by the present specification.

When air is flowing normally in the hose, a biasing element provides a biasing force to hold the valve closure element on its seat as shown in FIG. 30 and there is air flow provided of the one or more motors and the cyclones, providing suction and airflow. Without the valve, the air flows through the clean air inlets which is acceptable since there is provided excellent suction and airflow, but in experiments it has been found that the total airwatts delivered by the machine are slightly reduced.

As shown in FIG. 32, another pressure-responsive valve mechanism is provided and shown for use in an embodiment of the present technology. In this embodiment the pitot tube and the injector tube are integrated such that if there is a blockage in the hose, then the valve disk or piston, which have been in this embodiment integrated with a pressure-responsive valve actuator will be drawn away from a closed position to an open position so as to provide fresh air from outside the vacuum cleaner.

As shown in FIG. 34 the pressure-responsive valve mechanism has been replaced with an electronic valve actuator 81, which includes an electric motor, such as for example a servo motor, an electronic controller and a pressure sensor 82. The electronic controller 80 may be programmable or preprogrammed and autonomous, or it may be a relay switch, actuable by a command from a remote controller. The electronic controller may have some processing elements on board or it may have some other processing elements mounted on a remotely disposed control centre, such as one mounted on a board, and either wirelessly controlled, or wired and controlled with a relay. Thus, the remote or central or local controller may be a PLC, a PCB, a chip, a relay, an arduino, a raspberry pi, or other controller suitable for receiving pressure readings and the like from the diffuser or other place, including other nozzles and cyclonic filters disposed in the air circuit.

The electronic valve actuator will operate to provide variable control with a closed loop regime in accordance with the following description. First, when the sensor detects that vacuum pressure is at a high (negative) level in the diffuser, an instruction is given to actuate the valve. At that time, the vacuum pressure will further increase (become further negative) and when valve opens up more than a selected level—the vacuum pressure will reach a static level and the valve will stay open until the pressure changes.

The controller balances its inputs to find the optimum rate of nozzle valve closure element, diffuser width and throat internal diameter (if flexible throat used). The diameter of the nozzle can be varied as well (from 10-35% of the internal diameter of the diffuser). The diffuser's size is limited by the entire system size of path. In embodiments contemplated the diameter of the diffuser is about ϕ30-35 mm for standard home use vacuum cleaners. Thus, we can reduce the diameter of the throat but it is impractical to have a larger-diameter diffuser.

Under mechanical control, the valve has a similar performance but the electronic method is more sensitive and accurate. The valve closure element will not necessarily find and stay at the optimum position but will hunt around that optimum point a little, and this will depend on the feedback loop responds time. To inhibit this behavior, the electronic controller can use advanced control technique which sends a drive signal before the valve closure element moves, and before the valve closure element achieves the optimum position, send the opposite drive signal again. The signal oscillates, but the valve stays in the right position and noise is reduced. The controller in the embodiment shown uses a single chip microprocessor or analog circuit with RC or LC filter to smooth the valve closure element motion. For the mechanical controller, a mechanical damper can be used. The valve can be shaped to reduce vibration.

FIG. 35 shows a further embodiment of a valve, similar in operation and structure to that shown in FIG. 30 and discussed above, the valve similarly including a pitot tube and like components, but which includes a concertina membrane which assists in responding to the negative pressure in the pitot tube if it occurs in the system.

Variable Injector Throat Diameter

FIGS. 6 to 16 show a contractible throat 70 so as to improve the operation of the injector. The contractible throat 70 provides increased efficiency of the injector under selected conditions. The throat 70 is variable in diameter and includes a flexible and resilient throat body which is responsive to pressure. The throat body forms part of the wall of the diffuser in that a portion of the diffuser wall is replaced with the throat body along a selected length. In one embodiment the throat body is a length of rubber and is formed into the shape of a diffuser wall.

That is, where the diffuser wall is a square section, the throat body is square. That arrangement is shown in FIG. 9. The arrangement in those Figures is that of a regulator 60 which is in a closed position (letting no air through the injector) when air is flowing normally in the diffuser. When there is a blockage in the diffuser, the regulator is drawn by the low pressure to an open position to narrow the throat 70 of the diffuser. Fresh air is thereby drawn through the injector tube 42 which keeps air flow to the cyclone 14. The narrowing of the throat 70 by the regulator 60 assists in drawing more air through the injector until a balance is found. This regulator 60 is integrated with the valve so that one component may do two tasks—open the fresh air and also choke the diffuser duct 35 to accelerate the flow. This is a kind of synergistic effect and the valve is held open when the pressure stays low inside the diffuser duct 35.

For ease of manufacture of certain components the throat body 70 is cylindrical as shown in FIG. 10. The throat body 70 includes connecting elements 72 to connect to the wall of the diffuser at either of its ends. The connecting elements include flanges and fasteners. It is also possible that the throat body is moulded into the diffuser wall. It is also contemplated that portions of the wall may be sufficient to provide the improvement in efficiency—that is, strips of rubber across windows or apertures set into the diffuser wall may provide a benefit.

In one embodiment there are provided strengthening ribs along the length or around the circumference of the throat body. In one embodiment those strengthening ribs are in the form of springs, or other stiffening battens, disposed inside longitudinal pockets or attached to the outside or inside of the throat body.

The throat body in use, under negative pressure inside the diffuser 35, is drawn inwards, which has the effect of increasing the velocity of air inside the diffuser and increasing the pressure reduction further, drawing air in faster and providing greater efficiency of air draw along the clean air inlet 36. This may have the effect of shortening the length of the diffuser so a relief joint may be provided in one or more of the connecting elements such as the clean air duct 36 or the pitot tube. That joint may be a resilient mount or a slip joint, telescoping joint, or concertina sleeve, or like element.

Any mention of documents or technologies known before the filing date of this application is not to be taken as an admission that those documents or technologies were common general knowledge at the filing date of this application.

It is also to be understood that the word “comprise” and like grammatical variants including “comprising” are to be taken as inclusive and not excluding other components or features.

It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of technology as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive. 

1. A cyclone filtration assembly unit for mounting in a vacuum cleaner, the cyclone filtration assembly unit including: a housing having a housing inlet for a dirty air stream and a housing outlet for a filtered air stream; one or more cyclone separators mounted in the housing, each of the one or more cyclone separators comprising one or more cyclone separator inlets, at least one dirt outlet, and at least one clean air outlet in fluid communication with the housing outlet; and one or more injector units configured to deliver an airstream of clean air from outside the housing and dirty air from inside the housing to the one or more cyclone separator inlets, the injector unit comprising: a diffuser duct having an inlet end in fluid communication with the housing inlet to introduce dirty air from the housing inlet to the cyclone separator inlet, and an injector tube configured to inject clean air into the diffuser duct adjacent the inlet end, the injector tube being in fluid communication with a housing aperture at an inlet end to introduce clean air from outside the housing to the diffuser duct.
 2. The cyclone filtration assembly unit in accordance with claim 1 wherein the diffuser duct is a venturi arrangement, wherein adjacent the injector tube there is a throat portion being a restriction in the diameter of the diffuser duct.
 3. The cyclone filtration assembly unit in accordance with claim 1 wherein the diffuser duct includes an outlet in fluid communication with an associated cyclone separator, the diffuser duct being configured to mix the clean airstream with the dirty air stream.
 4. (canceled)
 5. The cyclone filtration assembly unit in accordance with claim 1 wherein the tortuous path is a helix.
 6. The cyclone filtration assembly unit in accordance with claim 1 wherein a valve is provided in fluid communication with the injector tube to control clean air inlet flow therethrough.
 7. The cyclone filtration assembly unit in accordance with claim 6 further including an electronic controller for the valve, the electronic controller being configured to respond to changes in pressure in the diffuser duct.
 8. The cyclone filtration assembly unit in accordance with claim 6 further including a valve closure element operatively connected to a pressure-responsive element that is responsive to changes in pressure in the diffuser duct.
 9. The cyclone filtration assembly unit in accordance with any one of claim 2 wherein the venturi throat portion or venturi restriction and the valve are integrally-formed so as to provide a variable choke in the diffuser duct and fresh air injection with a response to reductions in pressure in the diffuser duct.
 10. The cyclone filtration assembly unit in accordance with claim 9 further including a biasing element to bias the valve closure element, the biasing element disposed in a clean air duct.
 11. The cyclone filtration assembly unit in accordance with of claim 1 wherein the injector tube is angled relative to the diffuser duct so as to provide accelerated the dirty air in the diffuser duct.
 12. The cyclone filtration assembly unit in accordance with claim 6 wherein the throat section of the diffuser duct is variable in internal diameter in response to changes in pressure in the diffuser duct.
 13. The cyclone filtration assembly unit in accordance with claim 6 wherein the throat section of the diffuser duct includes flexible walls so as to vary the internal cross section area of the diffuser duct.
 14. The cyclone filtration assembly unit in accordance with claim 2 wherein a regulator is integral with the wall of the diffuser duct and arranged to respond to a low pressure in the diffuser duct by choking the throat.
 15. The cyclone filtration assembly unit in accordance with claim 14 wherein the regulator responds to low pressure in the diffuser duct by opening an aperture in the injector tube to allow fresh air into the diffuser duct.
 16. The cyclone filtration assembly unit in accordance with claim 1 wherein the injector tube is in fluid communication at the housing aperture to a vacuum cleaner motor to provide forced clean air induction through the injector.
 17. The cyclone filtration assembly unit in accordance with claim 1 wherein the injector unit is a De Laval nozzle arrangement such that the nozzle is a converging nozzle for delivering clean air to the diffuser, and there is then downstream from there, a diverging region for mixing and converting the kinetic energy of the flow to pressure.
 18. The cyclone filtration assembly unit in accordance with claim 17 wherein the diverging region is adjacent the dirty air inlet, and the diffuser duct then converges again to provide more kinetic energy and further mixing, and then downstream from the diffuser duct, at its outlet, delivery of the mixed fluid to the cyclone separator element.
 19. The cyclone filtration assembly unit in accordance with claim 1 wherein the injector inlet is angled at between 110 and 150 degrees to the diffuser duct to reduce pressure loss therein.
 20. The cyclone filtration assembly unit in accordance with claim 1 wherein the injector tube has a cross-sectional area of between about 15% and 35% of the cross sectional area of the diffuser duct to provide greater suction and efficiencies of filtering.
 21. A vacuum cleaner including: a hose and nozzle inlet for drawing dirt from a surface; a motor for drawing air through the hose and nozzle inlet; a cyclone filtration assembly unit in accordance with claims 1 to
 20. 22. (canceled)
 23. (canceled) 